Effects of Integrated Polysensory Recovery Treatment on the Functions of the Central and Autonomic Nervous Systems

Effects of Integrated Polysensory Recovery Treatment on the Functions of the Central and Autonomic Nervous Systems

E. N. Dudnik, O. S. Glazachev, O. Barak, A. A. Lavrishchev, and D. I. Kostyuk
Anokhin Institute of Normal Physiology, Russian Academy of Medical Sciences, Moscow, 125009 Russia
Faculty of Medicine, University of Novi Sad, Novi Sad, 21000 Serbia
Received December 26, 2007

Abstract — The changes in the parameters of P300 cognitive evoked potentials, the psychological and emotional state, and heart rate variability parameters reflecting the characteristics of autonomic regulation during polysensory physiotherapeutic recovery treatment were studied. A single treatment with combined polysensory stimuli resulted in substantial activation of sympathetic regulation of the heart rate, improvement of the emotional state, and an increase in the P300 amplitude in the central frontal areas, which indicates activation of cognitive processes.

INTRODUCTION

Potentiation and rapid recovery of the physical and psychophysiological working capacity to the optimal level is an important problem of preventive, sports, and military medicine, as well as occupational physiology [1, 2]. In recent years, development of new medical technologies for rehabilitation and recovery has been focused on integrated methods with multiple effects on the optimization of physical working capacity; neurohumoral regulation; stress resistance; and cerebral, mnestic, and mental functions [3]. The method of simultaneous combined treatment with a number of physiotherapeutic factors, such as heat, odors, music, vibration, and oxygenation, was demonstrated to be promising in several studies [4–6].

It is believed that the influence of a number of stimuli acting as eustress has a training effect; promotes stable brain function in a changing environment; minimizes the number of errors during solving of trivial and unusual tasks; and, as a result, optimizes the psychophysiological state and visceral functions [7, 8]. The effects of integrated treatment on visceral and psychomotor functions have been studied in detail; however, cerebral changes and modulation of cognitive functions have been studied more poorly because of technical and methodological difficulties. In most studies, the effects of physical and mental fatigue on cognitive functions and their recovery are described in terms of “response latency,” which is the final result of a mental process including perception of a stimulus; its identification, recognition, and assessment; choice of a response; decision making; and programming of the response, i.e., preparation of the motor system for movement [9, 10]. Brain functions associated with these stages of the cognitive process may be studied by recording brain potentials that are related to task solving and represent the final result of assembling different brain events induced by stimuli [11].

The recording of P300 endogenous cognitive evoked potentials (EPs) is one such approach. An EP is an overall index of brain electrical activity obtained by averaging the poststimulus EEG [12, 13]. Most authors consider P300 to be a neuroelectric cognitive phenomenon. Its appearance depends more on the subjective importance and information value of a stimulus than on its other physical parameters [14, 15]. The main structures responsible for P300 generation are the hippocampus, frontal lobe, and parietal lobe, and the P300 peak is related to the participation of the frontal lobes [12]. It is considered that the amplitude of the P300 complex represents attention resources used for task performance and updating of information in the working memory, whereas the latency of the P300 complex represents the rate of classification or time of action of a stimulus [16].

We investigated the cognitive EPs, the psychological and emotional state, and the parameters of heart rate (HR) variability (HRV) reflecting the specific features of autonomic regulation during polysensory physiotherapeutic recovery treatment. We hypothesized that integrated polysensory recovery treatment, acting as a eustressor and influencing homeostatic regulation and brain processes, stimulates cognitive functions and normalizes a person’s emotional state.

EXPERIMENTAL

The study was performed on ten subjects. The subjects were healthy, physically well-trained men aged 20–25 years regularly involved in aerobic sports (track and field and swimming). Each subject received, in random order, two rehabilitative and restorative treatments with a physiotherapeutic system, the Alpha Oxy Spa capsule (Sybaritic, United States). One treatment was with true polysensory stimuli and the other one was imitation. The subjects were not informed about the differences between these treatments. During each treatment, the subjects were in a lying position inside the capsule for 45 min. The treatment procedure included combined hyperthermic treatment (exposure to a high temperature (82°e), followed by a gradual decrease in temperature at a low relative humidity (8–15%) and additional air ionization with negatively charged ions); vibration massage of the thoracic and lumbar parts of the trunk, thighs, and shanks; oxygenation of the capsule with an oxygen flow at a rate of 4 l/min; relaxing music; and aromatic treatment with a relaxing mixture of orange, geranium, and ylang-ylang oils.

During imitation treatment, the subjects were placed into the capsule under relatively neutral conditions, which included relaxing, quiet music; a comfortable temperature of 33–34°e; and imitation of oxygenation by intensified blowing of ordinary air onto the subject’s face.

All participants were subjected to integrated examination before the start and after the end of each treatment. The examination was performed with the participant lying inside the capsule.

For assessment of the changes in cognitive functions, we recorded P300 late brain potentials using a Keypoint device (Medtronic, Denmark). The subjects performed two-tone audio tasks. During these tasks, series of randomly alternating high- and low-tone audio stimuli were presented through headphones with an intensity of 90 dB, a duration of 50 ms, and an interstimulus interval of 2 s [12]. One of the stimuli, a 1-kHz sound, was presented often (80% of presentations), serving as a background. The other stimulus, a 2-kHz sound, was presented more seldom (20%). The subjects were instructed to respond to the infrequent (target) stimulus by pressing a button that they held in the right hand and not respond to the frequent, background stimulus. The EPs were recorded using active electrodes placed along the midline of the head at the Fz and Cz points in accordance with the international 10–20 system and reference earlobe electrodes. The impedance of the electrodes was no higher than 5 kΩ. The signal was amplified by a factor of 30000 and filtered in the range of 1–100 Hz. The analysis epoch was 1000 ms for each derivation. We recorded no less than 60 target responses and 200 background responses of brain electrical activity for analysis. After that, only target responses were analyzed.

Identification of the P300 complexes and measurement of their parameters were performed blindly. The waves of brain potentials related to task performance were filtered with a low-frequency filter at 15 Hz. The maximum positive value of the P300 complex in the range 220–450 ms was regarded as the peak of the P300 complex. We measured the amplitude (EP300A) and latency (EP300L) of the P300 complex peak in each derivation. We also recorded the parameters of the sensorimotor response to target audio stimuli and calculated the percentages of correct responses (CR, %) and incorrect responses (IR, %) after nontarget stimuli and the response latency (RL, ms).

To monitor the characteristics of psychophysiological responses of the subjects to the integrated treatment, we estimated their emotional state. We assessed the levels of state depression (SD) and state anxiety (SA) and the degree of state discomfort (SDisc) using Spielberger’s scales adapted by Leonova et al. [17]. We performed an analysis of changes in neuroautonomic regulation by the method of tachogram recording using a VNS-Spektr device (Neurosoft, Russia). The HR was recorded for 5 min, and the time and frequency parameters of HRV were calculated in accordance with current standards [18, 19]. Analysis of the HRV power spectrum included calculation of the absolute total power (TP) of the HRV spectrum and parameters of the HRV power spectrum in the high-frequency (HF, %; respiratory waves), low-frequency (LF, %; slow waves of the first order), and very low frequency (VLF, %; slow waves of the second order) ranges. We calculated the index of vagosympathetic interaction LF/HF [19, 20]. We also calculated the temporal parameters of HRV, including HR (bpm); mode of the RR interval (Mo, ms), i.e., the most frequent value of the RR interval; amplitude of the mode (AMo, %), i.e., the number of RR intervals corresponding to the Mo value measured as a percent of the total size of the sample; the root mean square of successive differences between consecutive pairs of RR intervals (RMSSD, ms); and the percentage of consecutive RR interval pairs differing from each other by more than 50 ms (pNN₅₀, %). The tension index (TI) of regulatory systems was determined by the method of variation pulsometry [21].

The data were analyzed using the Statistica for Windows 6.0 software. The mean, standard deviation, standard error, and other parameters were calculated. The significance of differences was estimated with the use of the Mann–Whitney U-test.

RESULTS

We have found that, prior to true or imitation treatment, all subjects had parameters of cognitive EPs and sensorimotor responses within the range of conventional reference values [12]. Significant increases in the P300 amplitudes in both derivations were observed after polysensory treatment (Table 1). However, the values of the P300 peak latencies did not change significantly. The indices of sensorimotor responses, including CR, IR, and RL, also did not change during polysensory treatment. Imitation treatment did not signifi- cantly influence the parameters of cognitive EPs or sensorimotor responses.

Table 1. Changes in P 300 parameters after integrated polysensory and imitation treatments ( å ± m )

Notes: For abbreviations here and in Table 2, see the text.
* Significant difference from the data before treatment in the same groups ( p < 0.001).

Table 2. Changes in the parameters of the emotional state and autonomic regulation after combined polysensory and imitation treatments (M ± m)

* Significant difference from the data before treatment in the same groups (p < 0.05).

Prior to each type of treatment, we did not find any significant differences in the baseline values of the parameters of the psychophysiological state and autonomic regulation of HR between the subjects (Table 2). We compared the values of psychological indices with accepted reference values [17, 22] and found that, in our subjects, the emotional state was characterized by moderate SA and SD and a high SDisc. The initial values of the autonomic state parameters did not exceed the reference values; we estimated this state as normotonia, sympathetic and parasympathetic balance in regulation of the cardiovascular system.

After a single polysensory treatment, a significant decrease in SD was observed (Table 2). According to subjects' self-reports, they felt better and were in a better mood after polysensory treatment. The indices of autonomic regulation of HRV (RMSSD and pNN₅₀) were decreased, whereas the TI and HR, as well as the contribution of VLF%, were significantly increased. This state was estimated as parasympathetic depression and activation of sympathetic suprasegmental centers of autonomic control (Table 2).

After imitation treatment in the same capsule, the subjects did not exhibit any substantial changes in their psychological characteristics or parameters of autonomic regulation.

DISCUSSION

We have found that, in contrast to imitation treatment, a single combined polysensory treatment resulted in a significant increase in the ê300 amplitudes in the central frontal areas. We suppose that these changes were caused by activation of cognitive processes, including attention, operative memory, and decision making [12, 23]. The activation of cognitive functions was accompanied by improvement of the emotional state, which was evidenced by a decrease in subjectively estimated depression, substantial activation of sympathetic regulatory influences on blood flow, and moderate tachycardia. Similar changes in the ê300 parameters accompanied by a decrease in the anxiety level and induction of α activity in the baseline EEG were observed in studies on the effects of physical training and the level of training of the cardiovascular system on information processing in the CNS [10, 24] and accuracy of sensorimotor responses and ê300 parameters [13].

Although the neurobiological basis of cognitive EPs is disputable, it is believed that their parameters reflect the extent of involvement of brain resources in the analysis of incoming information with the participation of attention and operative memory [15]. In our experiments, attention and analysis of new information may have been potentiated due to simultaneous combined activation of a number of sensory channels, such as the channels of temperature, visual, auditory, and olfactory perception, together with increased oxygenation. The combination of these factors leads to an increase in the cerebral blood flow [10]. Hyperthermia in combination with oxygenation acts as a moderate stressor, which results in sympathetic activation, possible optimization of neurotransmitter functions, and activation shifts in the EEG [16].

CONCLUSIONS

Our data show that combined polysensory treatment with the Alpha Oxy Spa physiotherapeutic capsule (Sybaritic, United States) may be recommended for improvement of the restoration of cognitive processes in athletes, including activation of attention and operative memory and a decrease in emotional tension.

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